Babies are not all the same size. They are all born at different weights and lengths, so I would think it would be expected that they would vary in the womb, too. A week is not a huge deal at all. I'm measuring a week ahead, and I'm 100% sure of my dates. (I didn't always measure a week ahead either--it's changed over time.) Either I have a bigger than average baby, or the measurement isn't completely right, as ultrasounds become less accurate as time goes on.

I really would not be worried at all, unless it's a consistent decline or a very large difference.

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Mama to Julian Matthew 5/10/11

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